1. Field of the Invention
The present invention is related to an apparatus for controlling the traveling of a mower, and particularly to an apparatus the traveling speed of which is controlled in such manner that, when grass cut during a mowing operation is conveyed within a duct-like shooter, the shooter is not jammed with the grass.
2. Description of the Prior Art
Conventionally, in the traveling type working machine which works while traveling under power provided by an engine, traveling control has boon performed for automatically controlling the traveling speed according to the work lead condition. The following various improved methods have been proposed for such a working machine.
For instance, in the Japanese Patent Kokai 57-69148 official gazette, a method is shown for preventing unnecessary high-speed revolution at light loads and reduction in the number of revolutions at heavy loads by detecting the torque of a work lead to change the traveling speed of the working machine, thereby reducing fuel consumption. In the Japanese Patent Kokai 60-116008 official gazette. a method is disclosed for detecting the work load condition by the number of revolutions of the a.c. generator driven by the engine of the working machine to change the traveling speed of the working machine, thereby for keeping the appearance of the working trace good and preventing the working vehicle from operating in an overload condition. Further, in the Japanese Patent Kokai 62-69925 official gazette, a method is shown using a sensor for detecting the density of grass to be cut in the front part of the working vehicle and detecting (predicting) the work lead condition based on the sensor output, thereby to effectively utilize the engine output and efficiently perform a grass cutting work.
In the working machine wherein the grass cut in a cutter deck is forcibly conveyed by air blasting by a cutter blade or the like, as in the lawn mower using a grass-bag for instance, the cut grass is conveyed by the air flowing in the shooter, and thus there is a problem that the conveying capacity decreases as tile amount of grass to be cut and conveyed increases and the shooter is apt to be jammed with cut grass.
Once a jam phenomenon has occurred, continuation of the mowing work requires an operation for demounting the shooter and cleaning the portion where the jam has occurred, and then replacing the shooter. The work of removing the mowed grass and cleaning is very cumbersome and dirty, and thus is disliked by the worker and largely decreases the working efficiency.
If a jam occurs simply because the amount of grass mowed is too large, the amount of grass mowed can be decreased by automatically raising the level of the cutter deck to increase the mowing height. However, if the mowing height is controlled to increase each time a jam is to occur and decrease when the jam has been dissolved, then the mowing height is uneven and the appearance of the grass after the work or finish of the work becomes poor.
Besides, it has been found that the shooter is not always jammed with mowed grass because of its excessive amount or lead of the mower. For instance, if grass to be cut is wet and cut grass easily sticks to the inner surface of the shooter, or cut grass is conveyed in a lump within the shooter because of disturbance of the air flow, then a jam is often caused. Once a slight jam has occurred to interfere with the air flow within the shooter, it will soon lead to a heavy jam which makes the work impossible.
From the test result by a study for many years, the present inventors found that the jamming in the shooter with cut, grass is not simply due to a great amount of grass mowed, but is due to a decrease in the quantity of air flowing in the shooter as the density of cut grass extremely increases even temporarily, for instance, when the shooter begins to be jammed with cut grass. The inventors accordingly reached the conclusion that, to prevent the jamming of the shooter, it is important to control the density of cut grass passing within the shooter not to exceed a proper value and continue to ensure an optimum air flow quantity for the amount of cut grass to be conveyed.